Eliminating Revolver Cylinder Endshake

[Sharps40]

A very old S&W Mod 36. A Flat Latch. I still have the original numbers matching walnut grips, long ago sanded smooth and varnished for snag free concealment by the original LE owner.

A fine shooter with most of its original finish....just a touch of endshake in the cylinder. An easy remedy and this handgun will be as tight as new in 15 minutes.

The 10 thousands gauge is a very tight interference fit. The 9 thousands gauge just barely slips between cylinder and barrel with the cylinder held fully rearward. There is visible fore and aft shake in the cylinder along the yoke axle with the gauge removed. Too nice a gun to allow it to continute be battered with each shot.

Stainless steel shims, 2 thousands thick. They come in packs of 10 and I should only need one. So, since they are long lasting and I only need one....guess I'll have to find several more S&W revolvers to tighten up.....

Remove the yoke and cylinder from the frame.

Disassemble the extractor mechanism from the cylinder. On the J frame Smith, the threads are reversed....Righty Loosie, Lefty Tighty gets it apart.

 

[Sharps40]

A single endshake bearing is inserted. It fits in the bottom of the cylinder, under the large spring, surrounding the extractor shaft and bearing against the face of the yoke axle.

Install the extractor only into the stripped cylinder. Drop on a single endshake bearing.

Press the endshake bearing fully home with the yoke axle.

Reassamble the springs and extractor rods to the cylinder and test fit in the revolver. At this time, a 2 thousands shim makes it impossible to insert the 9 thousands gauge. The revolver function appears perfect with no drag and no endshake...so it appears only one shim is needed and no trimming of the axle is needed to allow for insertion of a full 2 thousands thick bearing.

A final check, 7 thousands is now a slightly snug fit. I won't add any more shims. Endshake is gone and the gun functions without snagging or hitching. If in 30 years it loosens up again, 2 stacked shims can be added but I doubt I'll ever have to get in there again! That's it. Done, this one is ready to go back to full duty service.

 

[TucsonDirt]

Cool step-by-step descriptions, will be useful by somebody I'm sure.
Thanks for posting!

 

[cadillo]

Just to add that as the shims are so thin, they should be generously oiled to make them last. I used to install them, but later switched over to stretching and then truing the crane barrel instead. Actually easier than installing the bearings, and as I shoot my double action revolvers a lot, it's just better for me that way.

Also, one should always insert empty cases or dummy rounds into the chambers prior to removal of the ejector rod and center pin of the cylinder, as the alignment pins are small and delicate. If they become bent, one has a very big problem. The cases/dummy rounds brace against the torque of unscrewing the ejector rod thus sparing the alignment pins.

 

[Doc Fillem]

Great tips guys!

 

[Carry_Up]

I think terminology is a bit confused here. Technically speaking, you have measured the b/c gap, not endshake. Correct b/c gap measurement is obtained whilst holding the cylinder to the rear. b/c gap will open up a bit with use, but considerably faster when using magnum or +P ammunition. That is because the rear ejector bearing surface is slammed against the bearing recoil face during firing, and eventually will peen and change dimension.

Endshake is the difference in b/c gap measurement between holding the cylinder back, and holding it forward. You do not want to eliminate endshake altogether, since that will bind the action. Installing the shim washer will open up the b/c gap, not close it. The apparent gap closure in your measurements may reflect the fact the the rear barrel face is not square to the frame. The only way to close up b/c gap is to set back the barrel.

Remember that b/c gap, endshake AND headspace (rear gauge) all must be checked together and are all inter-related.

Carry_up

 

[Sharps40]

Yep. and the endshake is removed with the install of the shim. Tight as new front to back, there was nominal rotation on the stop to begin with....ratchet is good, timing fine, range rods pass thru, and measuring the gap up front and conducting a bit of math is one way to get a feel for how much endshake there is.....you can also insert cartrides, measure it out back and do the math and compare. Overall, the goal was to show a very simple fix but not to confuse with lots of other methods, fixes, checks, etc. Since everything else on the gun was good, only the brutally simple fix of an endshake bearing was needed and so....showed it here. Natch, if the rest is out of spec, more work needs to be done and that's up to the owner/smith to determine. Nice thing is, once the endshake is minimized, it becomes easier to determine with accuracy and confidence if other interrelated items need work such as ratchet wear, hand wear, stop wear, ratchet slot wear, stop slot wear, cylinder notch wear, recoil shield wear at the ratchet contact point, etc, etc....but all that is beyond the scope of this most simplistic thread.

As for BC gap, it is what it is....resetting the barrel is also beyond the scope of this thread. In any event, tight or a bit loose, makes little difference on a belly gun....we won't be and it wasn't designed for potting squirrels in the head at 25m. The oft touted 4 thou might be a bit tight for a gun that needs to work in all conditions including dirty....i.e. carry....and 7 to 10 thou ain't bad, there is no significant additional spitting with 38 ammo and those gaps.

Sometimes the engine burns oil, but doesn't need an overhaul.....just a new set of valve stem seals and off you go for many thousands of reliable and safe miles......sometimes the gun just needs a shim.

Remember....simple fix, simple thread, one step of many possible for fixin up a revolver. For this one....minimized endshake, fair gap, good headspace, perfect function.....done/closed...thanks!